What are the other Names for this Condition? (Also known as/Synonyms)

• CH (Congenital Hypothyroidism)

What is Congenital Hypothyroidism? (Definition/Background Information)

• Congenital Hypothyroidism (CH) is a type of thyroid function disorder that presents itself right from birth or develops immediately following the birth of the child. In children born with this disorder, there is either partially or completely impaired thyroid gland function
• Hypothyroidism is a condition in which the thyroid gland (present in the neck) is underactive and produces low amounts of the hormone thyroxine, due to a variety of factors. This can result in several symptoms and complications, particularly if it is left undiagnosed and/or untreated
• Thyroxine is responsible for regulating the body's metabolism. It stimulates cells of the body to produce proteins, and also increases the amount of oxygen used by them. It also has a very important role in fetal brain development
• In some cases of children with Congenital Hypothyroidism, the thyroid gland may be underdeveloped or abnormally located. However, in about 85% of the cases, the thyroid gland is totally absent. Other factors that may influence onset of the condition include iodine deficiency during pregnancy, impaired pituitary gland function, and a family history of the disorder
• The signs and symptoms of Congenital Hypothyroidism include the presence of coarse facial features, feeding difficulties, constipation, weak muscle tone, hypothermia, poor sleep, and abdominal distention. A delay in diagnosis and/or treatment may severely impede normal physical and intellectual growth
• In most countries, early newborn screening for thyroid hormones (through blood tests) following birth of the child can help detect deficient levels of thyroid hormones. Following a diagnosis, treatment of the condition is immediately undertaken, which primarily involves thyroid hormone replacement therapy
• The prognosis of children with Congenital Hypothyroidism is generally excellent with adequate and prompt treatment, resulting in normal growth and development of the affected child. A delay in recognition and treatment of the disorder may lead to slow growth and mental impairment that may be irreversible

Who gets Congenital Hypothyroidism? (Age and Sex Distribution)

• The incidence of Congenital Hypothyroidism in newborns is estimated at between 1 in 2,000 to 1 in 4,000 cases
• The presentation of signs and symptoms of the condition may occur following the birth of the child (congenital presentation)
• Even though both genders are prone to the condition, more females than males are affected (female-male ratio is 2:1)
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Congenital Hypothyroidism? (Predisposing Factors)

Following are some of the risk factors for Congenital Hypothyroidism:

• Iodine deficiency in the mother during pregnancy is the most common predisposing factor
• Abnormal function of the pituitary gland (causing central hypothyroidism)
• Presence of genetic conditions leading to syndromic hypothyroidism such as:
  • Bamforth-Lazarus syndrome
  • Brain-lung-thyroid syndrome
  • Pendred syndrome
• A positive family history may be an important risk factor, since Congenital Hypothyroidism can be rarely inherited
• Gestational period over 40 weeks

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Congenital Hypothyroidism? (Etiology)

The cause of Congenital Hypothyroidism is mainly due to an abnormal development of the thyroid gland during pregnancy.

• It is observed that a vast majority of babies with the disorder have no thyroid gland at birth. In others, the gland is either poorly-developed, small-sized, or abnormally placed at another body site. An underdeveloped thyroid gland may be unable to produce sufficient quantities of the thyroid hormone, leading to hypothyroidism and a set of associated signs and symptoms
• Around 2-5% of children present a positive family history; but in the vast majority of cases, the condition develops sporadically. In between 15-20% of the cases, certain gene mutations have been identified
  • These include the PAX8 and TSHR genes, which are responsible for normal development of the thyroid gland during pregnancy
  • Mutations in DUOX2, SLC5A5, TG, and TPO genes are known to disrupt production of thyroid hormones
  • TSHB gene mutations are known to affect the synthesis of thyroid hormones
• Congenital Hypothyroidism may occasionally also be a manifestation (symptom) of a larger and more complex genetic condition. Examples of such genetic conditions include Bamforth-Lazarus syndrome and Pendred syndrome
• In some children, abnormalities in the pituitary gland (the master gland located in the brain) may cause an impaired stimulation of the thyroid gland causing low/deficient levels of thyroid hormone production

What are the Signs and Symptoms of Congenital Hypothyroidism?

The signs and symptoms of Congenital Hypothyroidism may vary from one child to another, and it can be mild or severe depending on the amount of shortage of thyroid hormones in the body. The rate of development of the signs and symptoms may be slow in many individuals, resulting in a delayed diagnosis of the condition.

The signs and symptoms may include:

• Abnormal facial features such as depressed nasal ridge, large forehead, coarse hair, and swollen eyelids
• Difficulty in feeding the child
• Constipation
• Distended abdomen; intestinal obstruction
• Umbilical hernia
• Disturbed sleep
• Low body temperatures (hypothermia)
• The child remains less active
• Hoarse cry
• Nasal congestion and sinusitis
• Neonatal jaundice that may be present for several days to weeks
• Poor muscle tone
• Anxiety and depression in older children
• Burning or pricking sensation
• Goiter causing swollen throat
• Low blood pressure

How is Congenital Hypothyroidism Diagnosed?

Congenital Hypothyroidism is diagnosed on the basis of the following information:

• Complete evaluation of medical history along with a thorough physical exam
• Assessment of the presenting signs and symptoms
• Prenatal screening tests
• Early newborn screening - measurement of T4 and TSH levels, via a blood test can help diagnose the condition
• Technetium thyroid scan
• Radioactive iodine uptake (RAIU) test
• Imaging studies as needed

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Congenital Hypothyroidism?

The complications of Congenital Hypothyroidism may include:

• Abnormalities involving the long bones or heart
• Presence of kidney stones
• Impaired vision and hearing
• Abnormal connection between the trachea (wind-pipe) and esophagus (food-pipe), termed tracheoesophageal fistula, which can be a life-threatening emergency
• Slow growth and development abnormalities
• Intellectual impairment
• Fabry disease (angiokeratoma corporis diffusum)

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Congenital Hypothyroidism Treated?

The treatment of Congenital Hypothyroidism may involve a team of healthcare providers from multiple specialties such as pediatrics, endocrinology, neurology, and obstetrics. An early detection and prompt treatment of the condition is important to avoid complications. The treatment, usually begun within the first few weeks of childbirth, may involve:

• Hormone replacement: Administration of thyroid hormone medications (thyroxine) to restore T3, T4, and TSH levels to normalcy
• Symptomatic treatment through medications and surgery, as needed
• Undertaking management of the underlying cause, if any present

A careful and periodic monitoring of pregnancy (including close fetal monitoring) is advised and recommended.

How can Congenital Hypothyroidism be Prevented?

Congenital Hypothyroidism may not be preventable in many cases. However, the following measures may be considered to reduce the risk for the same:

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Addressing any iodine deficiency before and during pregnancy
• Following the birth of the child, early newborn screening to assess thyroid hormone levels is recommended

Regular medical checkups with relevant tests and physical examinations are recommended during pregnancy.

What is the Prognosis of Congenital Hypothyroidism? (Outcomes/Resolutions)

The prognosis of Congenital Hypothyroidism is dependent upon the severity of the signs and symptoms and associated complications, if any.

• However, in a majority of cases, with early detection and treatment (thyroid hormone replacement), the physical and mental growth of children is normal
• In some cases, intellectual development may be affected in older children and adults
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications

In some cases, Congenital Hypothyroidism may be transient in nature. In children with the transient form (detected at birth), the disorder is temporary, and the body recovers to produce normal levels of thyroid hormone as the child grows.

Additional and Relevant Useful Information for Congenital Hypothyroidism:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/